An electronic device having an electronic component on a surface of a substrate has been proposed. The electronic device has a surface pattern that is electrically connected to a land and an external circuit on the surface of the substrate. Also, the electronic device has a solder resist that covers the surface pattern. The solder resist has an opening that exposes a portion of the substrate pattern connected to the external circuit. The electronic component is mounted on the land of the surface of the substrate through solder or the like. The surface of the substrate having the electronic component thereon is sealed with a molding resin in a state where at least the portion of the substrate pattern connected to the external circuit is exposed from the molding resin.
The electronic device described above is manufactured by the following method. Specifically, the land and the surface pattern are firstly formed on the surface of the substrate. After the surface pattern is covered with the solder resist, the opening is formed in the solder resist to expose a part of the surface pattern. Next, the electronic component is mounted on the land through the solder or the like. Then, a metal mold that has a recessed portion on a surface is prepared and the surface of the metal mold is pressure-welded to the surface of the substrate in a state where the electronic component is arranged in the recessed portion. Thereafter, the molding resin is inserted into a space between the substrate and the recessed portion of the metal mold. As such, a one-side-mounted electronic device (half-mold-type electronic device), in which the surface of the substrate having the electronic component is sealed with the molding resin, can be manufactured.
In the manufacturing of the electronic device, however, there is a case where air bubbles remain in the metal mold when the molding resin is inserted and the air bubbles are formed in the molding resin. In patent literature 1, a through hole is formed in the substrate to provide an air vent (air releasing portion). Since air can be released through the air vent when the molding resin is inserted, the air bubbles can be restricted from remaining in the metal mold.